The present invention relates to flat multiple pair electric cables and, more particularly, to apparatus for attaching connectors to the ends of such cables.
In U.S. Pat. No. 4,468,089 for "Flat Cable of Assembled Modules and Method of Manufacture", issued Aug. 28, 1984, on an application of William J. Brorein, and assigned to the same assignee as the present invention, there is disclosed a flat communication cable formed of an assembly of standardized modules in edge-to-edge relation surrounded by an overlying polyester protective cover. The modules containing a PVC jacket are united to form a ribbon by a blend of fusion and hot melt adhesive material, and the protective cover is bonded thereto by the adhesive. The modules can contain inter alia polyolefin insulated wire pairs, and the present invention is directed to apparatus for attaching end connectors to cable of that general category. As explained in said patent, the plastic covered or insulated conductors are non-adherently sheathed with a plastic sheathing material to produce the modules. The modules are, in turn, surrounded with a covering layer of plastic material to which they are adherently joined.
Several methods are described in the prior patent art for removing the outer insulating jacket from flat multi-conductor cable and these will be mentioned briefly hereinafter, but none is suitable for use with a Brorein cable. For example, in Garbis et al. U.S. Pat. No. 4,394,828, issued July 26, 1983, there is described a cable stripping tool that includes a blade with two cutting edges positioned in a common plane at a 60.degree. angle to each other and arranged to penetrate the cable from the cable end, slipping between the sheathing and the enclosed conductors, and simultaneously slitting the two longitudinal side edges of the cable sheathing. However, this tool assumes an unbonded condition between the jacketed or sheathed conductors and the outer sheathing.
In Toeppen U.S. Pat. No. 4,455,745, issued June 26, 1984, a flat cable is first placed between two cutting blades that can be brought toward each other to produce transverse cuts in the outer cable jacket while side cutters penetrate the side edges thereby producing a cut transversely about the entire periphery of the cable. Then a separate cutter is used to produce a longitudinal cut either between two spaced transverse cuts or between a transverse cut and the end of the cable whereupon the severed portion is peeled away to expose an underlying conductive shield. Again, the cable end preparation apparatus operates on the assumption that the outer jacket is not bonded to the underlying material.
Typical of a different approach to cable end preparation is Shields U.S. Pat. No. 4,439,631, issued Mar. 27, 1984. This patent describes a machine having a cutter for removing side portions of the cable, a grinding wheel for removing an insulating surface coating of the cable, and a scoring blade for scoring the underlying electrical shield that is subsequently broken away. The drawbacks implicit in this patented apparatus, at least for the purpose contemplated herein, will be evident after reading the description of the present invention to follow.
After stripping the outer jacket material from the individually insulated wires the individual wires have to be attached to an end connector. However, the known procedures and apparatus have serious limitations. Representative of the prior art are the devices disclosed in U.S. Pat. Nos. 3,742,571; 4,389,769; 4,453,307; and 4,243,288. The first three patents relate to tools for attaching wires to AMP Incorporated multi-contact connectors wherein the wires are attached one by one as the connector is advanced stepwise through the tool. The fourth patent requires the connector casing to be assembled about a connector core structure with all of the wires preformed to lie in respective parallel array planes for displacement simultaneously into the core structure. However, it will become apparent that such fitting and the wiring technique employed is not suitable for use with the Brorein cable mentioned above.